In the field of medicine, pathology is the study of the symptoms of disease. One of the most important applications of pathology is the study of individual human cells collected from symptomatic or asymptomatic patients. This subject of pathology is commonly regarded to as cytopathology or simply cytology. Properly applied, cytology can provide valuable and often crucial evidence of the presence and progress of disease. The well-known Papanicolaou test, commonly referred to as the Pap test, is a good example of a cytopathology application. Under the Papanicolaou test, a careful assessment of epithelial cells exfoliated from the uterine cervix can provide advance warning of pre-invasive lesions, and a this early stage of detection anyone of a host of treatments is available to arrest the cancer with a high degree of success.
It is realized that the vehicle for these cytological evaluations plays an important role in the accuracy and precision of disease diagnosis. Until recently, the accepted collection standard for a Pap test was a conventional smear. The smear involved simply wiping exfoliated cells onto a glass microscope slide before fixation. The conventional smear suffered a number of drawbacks, and has now given way to more rigid techniques which are based in the fluid collection, presentation and preparation of epithelial cells.
Although the specific techniques known in the art for process epithelial cells for preparing cytological samples differ in various degrees, they all begin with the collection of epithelial cells in a suitable preservation fluid. It will be appreciated that the immediate transfer of exfoliated cells to the preservation fluid can eliminate preparation artifacts such as air-drying effects which tend to distort and alter the appearance of the cells. Furthermore, the preservation fluid provides a vehicle for carrying the epithelial cells in suspension for subsequent processing steps.
As fluid-based specimen collection and preservation techniques began to supplant the conventional smear for the Pap test, it was learned that the most important advantage in the new techniques lay in the recovery of the epithelial cells. Early published studies using flow cytometry established that transfer efficiency for a conventional smear was typically less than 10%. The new fluid-based specimen collection techniques were able to increase the rate of specimen recovery through the simple step of rinsing the exfoliation instrument, e.g. a plastic spatula or brush, in the preservation fluid. This was the principal reason for the increase in the diagnostic accuracy associated with early mono-layer specimens.
While it has been found that rinsing the exfoliation instrument in the preservation fluid provides an effective method for transferring epithelial cells to the preservation fluid (i.e., collection fluid), the technique is not entirely efficient and there is room for improvement. First, efficiencies may be found in improving the efficiency of the rinsing mode itself. Secondly, the sheer variety of exfoliation instruments commonly in use by today's clinicians has failed to lead to a simple efficient technique for transferring the exfoliated cells. The most common exfoliation instruments in use today include a "broom" instrument, an exfoliation instrument which is a combination of a spatula and a brush, and an instrument known as the Combi.TM. device which incorporates elements of both previous devices.
Since the conventional simple rinsing action cannot provide an effective transfer technique for all of the known exfoliation instruments, there still remains a need for a method or apparatus for efficiently transferring exfoliated cells from these instruments to the preservation fluid. Accordingly, there is a need for a generalized device for fluid-based sampling systems capable of handling the different types known exfoliation instruments.